Example: bandit on my 6 with a high closure rate... I want to force him to overshoot by pulling the best possible break turn I can in my AC of choice. In a spit16 for example, would I fly close to 160 or would that number be higher to achieve my desired turn?
This would be at around 220 for Spixteen. If you look at the Excel sheet and mess with the numbers, you'll find most aircraft turn tighter at corner velocity than max sustained turn.
Definitions: corner velocity is the slowest speed at which you can pull max Gs. This is also the speed at which you can get the maximum instantaneous turn rate. That is, you will get the max turn rate, but only for a brief second. You can "sustain" corner velocity turn rates by turning nose low so that your speed doesn't fall during the turn.
Practical applications? Energy fighting - you bleed your opponent out of airspeed and energy. Say you are in symmetrical aircraft, both Spit9s. Somehow, whether through initial advantage or energy conserving flying, you are now both on the deck. However, he's turning at his sustained rate while you are flying a loose circle a little above him with enough energy to pull corner. If you time things properly, you can use your energy to pull in for angles to finish the fight. This will be because your higher turn rate will allow you to point your nose more quickly than he can maneuver out of the way. Ideally this would be done at corner velocity, but energy advantage can always be converted to angles.
Best sustained turn rate: this is the speed at which the aeordynamic drag from turning exactly matches the power output of your engine. This means that your turn is "in equilibrium" you are neither gaining nor losing energy assuming you turn level. This turn is always at the edge of stall hence why TnB can be referred to as stall fighting.
Applications: Turn/Angles fighting. If you have the higher turn rate, you'll be able to point your nose and take the shot better.